High arsenic groundwater is widely distributed in China,and it is of great significance to develop green and efficient arsenic removal materials for the sake of regional development and safety of drinking water for residents.In this study,the fly ash modified with manganese dioxide(MFA150)was prepared using co-precipitation method combined with NaOH hydrothermal process,to investigate its adsorption of As(Ⅲ)and As(Ⅴ)in groundwater.The results show that the vitreous structure of the raw fly ash was destroyed to generate zeolite phase in NaOH hydrothermal process,and the specific surface area of fly ash increased from 1.30 m2/g to 40.26 m2/g.After loading MnO2,the specific surface area of the adsorbent further increased to 148.82 m2/g,and the content of-OH on the surface was significantly increased to provide more adsorption sites for As(Ⅲ)and As(Ⅴ).The adsorption of As(Ⅲ)and As(Ⅴ)was in accordance with the Elovich model and the Freundlich model.The adsorption capacities of MFA150 for As(Ⅴ)and As(Ⅲ)under neutral condition were 2.55 mg/g and 9.71 mg/g,respectively,and showed stronger adsorption ability under acidic condition.Coexisting HCO3‒ and PO43‒ inhibited the adsorption of As(Ⅲ)and As(Ⅴ),while SO42‒slightly promoted the removal of As(Ⅲ)and As(Ⅴ).In simulated groundwater,the removal rate of total As reached 91.90％by MFA150.Since preparation of MFA150 is simple and the raw material is cheap and easy to obtain,MFA150 is expected to be used in the treatment of the high arsenic groundwater owing to the better adsorption performance for As(Ⅴ)and As(Ⅲ).
high arsenicgroundwaterfly ashmanganese oxideadsorptionresource utilizationenvironmental geology
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